The concentration profiles of high-dose implanted N+ (5×1017 atom/cm2, 100 keV) in iron foils (about 4000? thick) and iron bulk sample (industrial purity) were measured by E. B. S. via α-particle of energy in order of MeV. A dip was found in backscat-tering spectrum of the substrate, as a result of the high-dose impurity, implantation a method was developed to calculate the concentration profile of impurity based on the dip.